The Web Ontology Working group has a requirement...
"R9. Data types
The language must provide a set of standard data types. These
data types may be based on XML Schema data types."
--
http://www.w3.org/TR/2002/WD-webont-req-20020708/#section-requirements
In working out a design for this requirement, we found
it straightforward, with a few exceptions, to integrate
the built-in datatypes, since the XML Schema spec gives them URIs.
The exceptions were types like QName, which don't
fit the mold of a lexical space of strings with
an unambiguous mapping to values. I raised
this issue a while ago...
QName is ambiguous; aren't datatypes unambiguous? union types total?
From: Dan Connolly (connolly@w3.org)
Date: Fri, Aug 02 2002
http://lists.w3.org/Archives/Public/www-xml-schema-comments/2002JulSep/0056.html
But the XML Schema spec doesn't give URIs for types
like "integers between 10 and 20", i.e. derived
datatypes.
A precursor to OWL, DAML+OIL, used
schemadoc#typename
to refer from ontologies to datatypes;
e.g. to constrain the range of a property.
[hmm... where is that documented? I can't
find it.]
But the XML Schema spec doesn't specify that
URIs of that form refer to datatypes, so we don't
think it's best to include that mechanism in
our design at this time.
We understand the XML Schema WG is working on
a design for URIs for user-defined datatypes.
If the design you're working on will be compatible
with the simple schemadoc#typename syntax,
please let us know, and we'll use that.
But we understand it's likely to be different
(because of the difference between schema
documents and schemas, the different kinds
of names in schemas, etc.) so we're leaning
toward postponing (part of) this issue 'till the next
version of OWL.
http://www.w3.org/2001/sw/WebOnt/webont-issues.html#I5.8-Datatypes
The case of URIs for user-defined datatypes is, perhaps,
a specific case of the general issue of URIs for
schema components...
TAG interested in progress on URIs for schema components (NUNs)
From: Dan Connolly (connolly@w3.org)
Date: Thu, Oct 17 2002
http://lists.w3.org/Archives/Public/www-xml-schema-comments/2002OctDec/0011.html
--
Dan Connolly, W3C http://www.w3.org/People/Connolly/